Locking orifice retaining nut

ABSTRACT

An inlet manifold for use with a heat exchange device such as a cold plate in which the manifold includes a main passage for transferring liquid. The main passage includes a seat sized to hold an orifice plate for restricting the transfer of liquid to a flow suitable to produce a pressure drop. An orifice plate retaining element contacts the orifice plate to maintain the orifice plate on the seat, and has a locking element to prevent unlocking during use.

STATEMENT OF GOVERNMENT INTEREST

This invention was made with government support under NNJ06TA25C awarded by NASA. The government has certain rights in the invention.

BACKGROUND

Heat exchangers are conventionally used to heat devices that require heat or cool devices that produce heat that needs to be removed. One example of a heat exchanger is known as a cold plate, which is used, for example, to cool electronic units that produce heat while being operated. The heat needs to be removed to permit the electronic components to continue functioning.

One concern about the use of cold plates is that when orifices are used to control the pressure drop or flow rate, the orifices have been retained in bolted housings that require seals. This introduces potential leak points into the system. Often it is necessary to adjust or control the pressure drop or flow rate specifically for a particular end use, so the cold plate cannot be used without a method of making that adjustment or control. If the cold plate is intended for use in extreme environments, such as in outer space, the seals are particularly vulnerable and the potential for leakage prohibits their use.

An alternative way to control the pressure drop or flow rate in cold plates is needed to permit use of cold plates in extreme environments.

SUMMARY

The present invention is a device for adjusting fluid flow in cold plates and other fluid flow heat exchangers to obtain a desired pressure drop without the use of seals. The device includes an orifice that provides the desired fluid flow, thus controlling coolant pressure drop inside a cold plate. Different orifices are employed until the one is found that has the appropriate internal diameter to provide the desired pressure drop. During testing, the orifice is secured with a non-locking orifice nut. Once correct orifice size is determined, the orifice is secured using a nut with a locking element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cold plate used to actively cool electronic boxes.

FIG. 2 is a perspective view of the other side of the cold plate of FIG. 1.

FIG. 3 is an exploded view of a section of one of the cooling tubes of the cold plate showing the device used to control the pressure drop inside the cold plate of FIG. 1.

FIG. 3A is a perspective view of one component in FIG. 3.

FIG. 4 is an enlarged view of an orifice retaining nut.

FIG. 5 is a perspective view showing two cold plates bolted to a vehicle structure.

FIG. 6 is a perspective view showing the addition of boxes to be cooled by the cold plates shown in FIG. 5.

DETAILED DESCRIPTION

FIGS. 1 and 2 show cold plate 11 with surface 13 for cooling electronic units that require cooling to function. Cooling liquid inlet manifold 14 has inlets 15A, 15B and outlets 16A, 16B. Cooling liquid outlet manifold 17 has inlets 18A, 18B, outlets 19A, 19B. Coolant flows through inlets 15A, 15B to outlets 16A, 16B into cold plate tube coolant loops 20A, 20B, respectively. Coolant flows out through loops 20A, 20B to inlets 18A, 18B of outlet manifold 17, and then out through outlets 19A, 19B. Loops 20A and 20B are held in place with loop mounts 23, as seen in FIG. 2. Manifolds 14 and 17 each are shown as having two inlets and two outlets, but one or many inlets, loops and outlets can be used, depending on design considerations. In every inlet manifold, the pressure drop (and thus flow rate of coolant) is controlled by the present invention. Inside cold plate tube manifold inlets 15A and 15B are orifices that provide for the required pressure drop for a desired fluid flow rate.

FIG. 3 illustrates one cooling liquid inlet manifold assembly 14 which includes inlet 15A, tube 27, orifice retention bore 29, orifice plate mounting seat 31, outlet passage 33, outlet 16A, orifice plate 37, and orifice retaining nut 39. Cooling fluid flows in inlet 15A through inlet passage 27, through retaining nut 39 and orifice plate 37, to outlet passage 33 and outlet 16A.

Orifice plate 37, shown alone in FIG. 3A, is positioned within orifice retention bore 29 against mounting seat 31. Orifice retaining nut 39 holds orifice plate 37 in place against mounting seat 31. Center bore 40 of retaining nut 39 is aligned with orifice 37A of orifice plate 37.

Orifice retention bore 29 has threads 29A on its inner wall to engage external threads 39A on orifice retaining nut 39. A smaller diameter portion 41 extends from retaining nut 39 into a reduced diameter portion of retention bore 29 and holds in place orifice plate 37. Orifice plate 37 and retaining nut 39 may be made from any solid material. Stainless steel has been shown to be effective for both elements.

Orifice retaining nut 39 also includes locking strip 43. One locking strip that has been effective is a KEL-F® PCTFE strip as defined in AMS 3650, which is standard for locking screws and bolts. KEL F® is a 3M registered trademark for a polychlorotrifluoroethylene polymer and has an operating temperature range of −320° F. (−196° C.) to +390° F. (199° C.). A slot is cut in threaded portion 39A of locking nut 39, typically about 0.020 inches (0.08 mm) and filled with a strip of the polymer. Flared inlet 40A of center bore 40 guides fluid from inlet passage 27.

During assembly of cold plate 11, orifice plates 37 having different sized orifices 37A are put in inlet manifolds 15A and 15B, as shown with manifold 15A in FIG. 3. Orifice plate 37 is held in place with a non-locking orifice nut, which is identical to orifice retaining nut 39 except that it is without locking strip 43. The coolant pressure drop is measured with different orifices 37A until the one is found that provides the desired or required pressure drop. The non-locking orifice nut is removed and orifice retaining nut 39 is inserted, with locking strip 43, such as by use of a screwdriver in slot 39B. Locking strip 43 is activated simply by screwing locking nut 39 into threads 29A of orifice retaining bore 29. Locking strip 43 prevents movement of locking nut 39 under normal vibration and other forces. Cold plate 11 is now ready for installation in a vehicle such as a space station or other orbiting vehicles.

FIG. 5 shows two cold plates 11A and 11B mounted on a portion of vehicle structure 49 after the orifices are installed and locked in place as described above. Inlets 15A, 15B and outlets 19A, 19B of each cold plate 11A, 11B are then welded to the vehicle plumbing (not shown but conventional). FIG. 6 shows that box 51 and box 53 are secured directly into vehicle structure 49 but boxes 51 and 53 containing electronic elements to be cooled are not fastened to cold plates 11A and 11B. Non-structural cold plates, not shown, mount boxes 51 and 53 to vehicle structure 45.

The cold plate system of this invention permits controlled cooling of individual electronic units base upon the needs of the unit through selection of the appropriate orifice diameter determined through pre-installation testing. After final installation, the electronics are now protected from heat generated during operation of the electronic components.

While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims. 

1. An inlet manifold assembly, the assembly comprising: an inlet; an outlet; a main passage for transferring liquid from the inlet to the outlet, the main passage having a seat; an orifice plate in the main passage seat for controlling flow of liquid the main passage; and an orifice plate retaining element contacting the orifice plate to maintain the orifice plate on the seat.
 2. The assembly of claim 1, wherein the seat is located in the main passage at a reduced diameter sized to hold the orifice plate.
 3. The assembly of claim 1, wherein the orifice plate retaining element and the main passage have mating threads for locating the retaining element.
 4. The assembly of claim 3, wherein locking element comprises a strip of polychlorotrifluoroethylene in a strip cut in a threaded portion of the retaining element and extends out from the strip to engage the threads on the main passage.
 5. The assembly of claim 1, wherein the orifice plate and the retaining element are made from stainless steel.
 6. The assembly of claim 1, wherein the orifice plate has a centrally located orifice; and the retaining element includes a central bore that is aligned with the main passage and the orifice.
 7. A cold plate device for use to cool objects, the device comprising: a plate member having a first and second side; a cooling tube loop mounted on the first side of the plate member; an inlet manifold having an inlet and an outlet for transferring cooling fluid to the cooling tube from the inlet to the outlet, the at least one inlet manifold having a seat located therein; an orifice plate positioned on the seat in the inlet manifold for controlling flow of cooling fluid into the cooling tube loop; a retaining element mounted in the inlet manifold for holding the orifice plate in fixed position; and an outlet manifold for transferring cooling fluid out of the cooling tube loop.
 8. The device of claim 7, wherein the seat is located in a main passage of the inlet manifold at a reduced diameter sized to hold the orifice plate.
 9. The device of claim 7, wherein the orifice plate has a centrally located orifice; and the retaining element includes a central bore that is aligned with the main passage and the orifice.
 10. The device of claim 7, wherein the orifice plate retaining element and the main passage have mating threads for locating the retaining element.
 11. The device of claim 10, wherein the retaining element including a locking element preventing removal of the retaining element.
 12. The device of claim 11, wherein locking element comprises a strip of polychlorotrifluoroethylene in a strip cut in the threaded portion of the retaining element and extending out from the strip to engage the threads on the main passage.
 13. The device of claim 7, wherein the orifice plate and the retaining element are made from stainless steel.
 14. A method for selecting the flow rate of cooling fluids in a cold plate having a plate member having a first and second side and a cooling tube loop mounted on the first side, an inlet manifold transferring cooling fluid to the cooling tube loop and having a seat, the method comprising: mounting an orifice plate on the seat in the inlet manifold to regulate the flow of cooling fluid into the at least one cooling tube; holding the orifice plate with a retaining element mounted in the inlet manifold in fixed position; and transferring cooling fluid through the cooling loop.
 15. The method of claim 14, wherein the seat is located in the main passage at a reduced diameter sized to hold the orifice plate.
 16. The method of claim 14, wherein the orifice plate is selected by testing a plurality of orifice plates having different bore sizes, the plurality of orifice plates being held in place for testing with a temporary retaining element.
 17. The method of claim 14, wherein the orifice plate retaining element and the main passage have mating threads for locating the retaining element.
 18. The method of claim 17, wherein the retaining element includes a locking element preventing removal of the retaining element.
 19. The method of claim 18, wherein locking element comprises a strip of polychlorotrifluoroethylene in a strip cut in the threaded portion of the retaining element and extending out from the strip to engage the threads on the main passage.
 20. The method of claim 14, wherein the orifice plate and the retaining element are made from stainless steel. 